It is customary in the glass manufacturing industry and, in particular, in the manufacture of glass containers to coat the container in order to impart wet and dry scratch and abrasion resistance to the glass surface to decrease breakage during handling, thus increasing the useful life of the container.
The most commonly used protective coating for glass containers consists of a first coating of a tin or titanium oxide which is applied to the container prior to its passing through the annealing lehr followed by a second coating of an organic resin applied to the container after passage through the lehr. This combination of a metal oxide "hot end" coating and an organic resin "cold end" coating imparts both satisfactory abrasion resistance as well as lubricity to the container surface.
This coating system, however, is disadvantageous in that the coating must be applied in two discrete applications, is expensive from the standpoint of cost of starting materials and application, and poses a serious pollution control problem since hydrogen chloride vapors are generated in the application of the tin or titanium coating.
It would be desirable to develop a coating that imparts both scratch resistance and lubricity that can be applied in a single application step and which would eliminate the attendant pollution problems inherent in the dual coating system. Such single step coatings have been developed, one of which is described in U.S. Pat. No. 3,873,352 which, however, has not proven commercially satisfactory in practice.
It is the principal object of this invention to provide a coating composition for application to glass containers which will impart both abrasion resistance and lubricity to the glass surface. It is another object of this invention to provide a coating composition that is applied in one step at the cold or exit end of the annealing lehr. It is a further object of this invention to provide a coating composition that is relatively inexpensive both from the standpoints of cost of starting materials and ease of application.